From: Alan Brady <[email protected]>
Date: Mon, 5 Feb 2024 19:37:55 -0800
> This starts refactoring how virtchnl messages are handled by adding a
> transaction manager (idpf_vc_xn_manager).
[...]
> +/**
> + * idpf_vc_xn_exec - Perform a send/recv virtchnl transaction
> + * @adapter: driver specific private structure with vcxn_mngr
> + * @params: parameters for this particular transaction including
> + * -vc_op: virtchannel operation to send
> + * -send_buf: kvec iov for send buf and len
> + * -recv_buf: kvec iov for recv buf and len (ignored if NULL)
> + * -timeout_ms: timeout waiting for a reply (milliseconds)
> + * -async: don't wait for message reply, will lose caller context
> + * -async_handler: callback to handle async replies
> + *
> + * @returns >= 0 for success, the size of the initial reply (may or may not
> be
> + * >= @recv_buf.iov_len, but we never overflow @@recv_buf_iov_base). < 0 for
> + * error.
> + */
> +static ssize_t idpf_vc_xn_exec(struct idpf_adapter *adapter,
> + struct idpf_vc_xn_params params)
Why do you pass @params by value, i.e. whole 56 bytes per each function
call instead of passing it by pointer -> 8 bytes per call?
> +{
> + struct kvec *send_buf = ¶ms.send_buf;
> + struct idpf_vc_xn *xn;
> + ssize_t retval;
> + u16 cookie;
> +
> + xn = idpf_vc_xn_pop_free(&adapter->vcxn_mngr);
> + /* no free transactions available */
> + if (!xn)
> + return -ENOSPC;
> +
> + idpf_vc_xn_lock(xn);
> + if (xn->state == IDPF_VC_XN_SHUTDOWN) {
> + retval = -ENXIO;
> + goto only_unlock;
> + } else if (xn->state != IDPF_VC_XN_IDLE) {
> + /* We're just going to clobber this transaction even though
> + * it's not IDLE. If we don't reuse it we could theoretically
> + * eventually leak all the free transactions and not be able to
> + * send any messages. At least this way we make an attempt to
> + * remain functional even though something really bad is
> + * happening that's corrupting what was supposed to be free
> + * transactions.
> + */
> + WARN_ONCE(1, "There should only be idle transactions in free
> list (idx %d op %d)\n",
> + xn->idx, xn->vc_op);
> + }
> +
> + xn->reply = params.recv_buf;
> + xn->reply_sz = 0;
> + xn->state = params.async ? IDPF_VC_XN_ASYNC : IDPF_VC_XN_WAITING;
> + xn->vc_op = params.vc_op;
> + xn->async_handler = params.async_handler;
> + idpf_vc_xn_unlock(xn);
> +
> + if (!params.async)
> + reinit_completion(&xn->completed);
> + cookie = FIELD_PREP(IDPF_VC_XN_SALT_M, xn->salt) |
> + FIELD_PREP(IDPF_VC_XN_IDX_M, xn->idx);
> +
> + retval = idpf_send_mb_msg(adapter, params.vc_op,
> + send_buf->iov_len, send_buf->iov_base,
> + cookie);
> + if (retval) {
> + idpf_vc_xn_lock(xn);
> + goto release_and_unlock;
> + }
> +
> + if (params.async)
> + return 0;
> +
> + wait_for_completion_timeout(&xn->completed,
> + msecs_to_jiffies(params.timeout_ms));
> +
> + /* No need to check the return value; we check the final state of the
> + * transaction below. It's possible the transaction actually gets more
> + * timeout than specified if we get preempted here but after
> + * wait_for_completion_timeout returns. This should be non-issue
> + * however.
> + */
> + idpf_vc_xn_lock(xn);
> + switch (xn->state) {
> + case IDPF_VC_XN_SHUTDOWN:
> + retval = -ENXIO;
> + goto only_unlock;
> + case IDPF_VC_XN_WAITING:
> + dev_notice_ratelimited(&adapter->pdev->dev, "Transaction
> timed-out (op %d, %dms)\n",
> + params.vc_op, params.timeout_ms);
> + retval = -ETIME;
> + break;
> + case IDPF_VC_XN_COMPLETED_SUCCESS:
> + retval = xn->reply_sz;
> + break;
> + case IDPF_VC_XN_COMPLETED_FAILED:
> + dev_notice_ratelimited(&adapter->pdev->dev, "Transaction failed
> (op %d)\n",
> + params.vc_op);
> + retval = -EIO;
> + break;
> + default:
> + /* Invalid state. */
> + WARN_ON_ONCE(1);
> + retval = -EIO;
> + break;
> + }
> +
> +release_and_unlock:
> + idpf_vc_xn_push_free(&adapter->vcxn_mngr, xn);
> + /* If we receive a VC reply after here, it will be dropped. */
> +only_unlock:
> + idpf_vc_xn_unlock(xn);
> +
> + return retval;
> +}
[...]
Thanks,
Olek
